1. Field of the Invention
The present invention relates to user terminals, Layer 2 switches (L2SWs), and Layer 2 gateways (L2GWs) to which VLAN IDs can be dynamically assigned in network systems that can be connected to an Ethernet (registered trademark) network.
2. Description of the Related Art
In recent years, corporate LANs and other networks have a virtual group of certain terminals built as a virtual LAN (VLAN), independently of the physical structures of the networks. This technology allows a network to be built, irrespective of a change in terminal location or a change in network configuration caused by an organizational change. The network management cost can be reduced, and the network load can be reduced due to a broadcast packet limitation.
One method of building a VLAN is to identify a VLAN by adding a VLAN tag to an Ethernet (registered trademark) frame header. This tag VLAN method allows a plurality of VLAN connections to be specified among apparatuses, giving flexibility to network configurations.
When a user terminal is connected to an existing VLAN, the connection information must be specified to each apparatus on the VLAN, such as a hub. The generic attribute registration protocol (GARP) VLAN registration protocol (GVRP) (non-patent document 1) enables a dynamic connection of a terminal to a VLAN when the terminal is connected. This protocol broadcasts a connection request from the terminal to the VLAN, and the apparatuses in the VLAN configure the VLAN setting sequentially according to the information.
A “Switching Hub with Default VLAN Configuration Function and VLAN Server” (patent document 1) has a function to connect a terminal which has not yet been registered to a system to a particular VLAN through a switching hub and to transfer the connection information to another switching hub.
Non-patent document 1: IEEE std802. 1Q-1998 (chapter 11, pp. 77-92)
Patent document 1: Japanese Unexamined Patent Application Publication No. Hei-11-215152